Bituminous sheet for use as water and dampness-insulating reinforcement material

ABSTRACT

A bituminous sheet for use as a water- and dampness-insulating reinforcement material for various types of constructions. The sheet is comprised of a nonwoven web of randomly arranged irregularly overlying straight synthetic staple fibers having an average length of at least 50 mm. and having a fineness measurement ranging from one-half to 20 denier. A binder material fixes the fibers with respect to one another so as to make the web into a matlike, nonwoven fabric. A bituminous material is interspersed between and around the fibers and/or fills substantially all of the voids of the fabric.

United States Patent Inventors Ellchi Tajima 15, 4-Chome, Komagome, Toshlma-ku; Kaname Yamamoto, 3-5, 6-Chome, Nishiogu, Arakawa-ku, both of Japan 738,806

June 21, 1968 Nov. 2, 1971 Dec. 26, 1967 Japan Continuation-impart of application Ser. No. 558,121, June 16, 1966, now Patent No. 3,403,425.

BITUMINOUS SHEET FOR USE AS WATER AND DAMPNESS-INSULATING REINFORCEMENT MATERIAL 3 Claims, No Drawings Int. Cl.

[50] Field oiSearch 16l/151, 152, 153, 156, 168, 170, 236, 82; 117/140, 138.8 W, 138.8 F, 168

[56] References Cited UNITED STATES PATENTS 2,811,769 11/1957 Craig 161/170 2,904,453 9/1959 Labino 161/170 3,063,787 11/1962 Rynkiewicz 161/172 3,252,822 5/1966 Burns 161/170 Primary Examiner- Robert F. Burnett Assistant Examiner-James J. Bell Attorney-Woodhams. Blanchard & Flynn ABSTRACT: A bituminous sheet for use as a waterand dampness-insulating reinforcement material for various types of constructions. The sheet is comprised of a nonwoven web of randomly arranged irregularly overlying straight synthetic staple fibers having an average length of at least 50 mm. and having a fineness measurement ranging from one-half to 20 denier. A binder material fixes the fibers with respect to one another so as to make the web into a matlike, nonwoven fabric. A bituminous material is interspersed between and around the fibers and/or fills substantially all of the voids of the fabric.

BITUMINOUS SHEET FOR USE AS WATER AND DAMPNESS-INSULATING REINFORCEMENT MATERIAL CROSS REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of our copending application Ser. No. 558,12l filed June I6, 1966, now U.S. Pat. No. 3,403,425.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waterproof bituminous sheet, and more particularly, it is concerned with a bituminous sheet for use as a waterand dampness-insulating reinforcement material in constructions which are given a waterproofing treatment. More particularly, the invention is related to a bituminous sheet which is manufactured according to a manufacturing procedure comprising the steps of first preparing a nonwoven web in the form of sheet or mat with a principal material consisting of randomly arranged irregularly overlying straight (crimpless or slightly crimped) synthetic fibers having good heat resistivity, such as polyester fibers or polyvinyl alcohol fibers, having an average length of 50 mm. or more, preferably on the order of I20 mm. or over, and having a fineness measurement of ranging from one-half to several scores of denier, thereafter fixing said web with a small amount of an appropriate binder solution so as to render said web to a unique matlike nonwoven fabric form, and then impregnating the resulting web with a molten bitumen of good quality, such as blown asphalt.

2. Description of the Prior Art Bituminous sheets for reinforcement have been used in the past in the portions of buildings which required waterproof treatment such as for example, the roofs of buildings, the floors and walls of basement rooms requiring waterproof treatment or dampnessproof treatment, or in the construction of underground passages and subways" which also required waterproof and dampnessproof treatment, or for such purposes as shutting out water at facilities such as harbors, aqueducts, and water reservoirs. Such reinforcement sheets have included bituminous felts or like products which were manufactured by impregnating a base sheet material consisting of porous and bulky paper with a fluid saturant which might be either molten coal tar pitch or straight asphalt. Such sheets have also included sheet form products which were manufactured by subjecting a base material consisting of a fabric made of jute or cotton staple fibers to processing or treatment with a molten bitumen, and have further included those products which were manufactured by subjecting a base material consisting of a mat made with glass fibers to an impregnation treatment with a molten bitumen.

However, these bituminous sheet-form products of the prior art invariably had advantages and disadvantages with respect to their properties and, therefore, none of them could be termed as being perfectly satisfactory for use as the reinforcement material in constructions requiring waterproof treatment.

First, a description of a bituminous felt will be given. The base material of the bituminous felt consists of paper and contains in its structure a considerably large amount of fibrilliform fine staple fibers which provides mechanical strength. For this reason, even though the paper is made with a bulkiness and porosity which are both considerably greater than those of ordinary types of paper, said base material consisting of such paper is of a structure wherein the spaces or voids form ed between the individual staple fibers are extremely fine. Therefore, in order to successfully impregnate such a paper having therein numerous fine voids with a molten bitumen, it has been necessary selectively to use a bitumen which exhibits a low viscosity when it is molten by the application of heat thereto, so that the bitumen is allowed to permeate thoroughly into these fine spaces or voids and fill them. To this end, coal tar pitch or straight asphalt has been generally used. Because the voids fonned between the fibers which constitute said type of paper of the prior art were so fine and narrow it was difficult to completely fill these fine voids even where a saturant or immersion fluid consisting of the aforesaid bitumen was used, and it was unavoidable that a considerable number of voids were left unfilled with the molten bitumen.

Bitumens of the aforesaid types in general showed a high susceptibility to changes in temperature, hereinafter referred to for convenience as thermosusceptibility, and accordingly, they had the drawback that, when subjected to an elevated temperature, they were easily softened and fluidized, and on the other hand, they soon became hardened and brittle when exposed to a low temperature.

For the foregoing reasons, the bituminous felts of the prior art which were manufactured by impregnating the aforesaid type of paper with the aforesaid saturant or immersion fluids had the drawbacks that they tended to become hardened and brittle to a marked degree when exposed to low temperatures and that, thus, they would easily lose their flexibility. In addition, in view of the fact that the base materials were made of a thick and bulky paper, these bituminous felts lacked pliability so that when they were bent with a substantial amount of force, they were very easily broken. Furthermore, conventional bituminous felts had relatively low mechanical tension and tear strengths. Still further, the bituminous felts of the prior art had a very small extensibility such that when they were pulled, they hardly elongated, but, instead, they were easily torn apart. Such properties of a bituminous felt are undesirable for a waterand dampness-insulating reinforcement material which is to be used in constructions wherein there are portions which are liable to receive external stresses.

Furthermore, if said paper base material consisted of organic natural staple fibers, the resulting bituminous felt had the fatal drawback of the presence of a considerable number of voids in the base material even after having been subjected to the process of saturation with a molten bitumen as previously mentioned. Such voids would permit the felt easily to absorb moisture and whenever it absorbed moisture, the fibers contained therein would become swollen and cause an expansion of the felt as a whole. Furthermore if such a bituminous felt was left in contact with water for an extended period of time, the felt would gradually and progressively decay resulting in a marked loss in its original mechanical strength.

A description will next be given concerning those waterproof reinforcement sheet-form products which were made by subjecting woven fabrics made with spun staple fibers of jute or cotton to processing with a molten bitumen. It is to be noted first of all that when these fibers are spun into a yarn, the fibers are placed together and then they are tightly twisted so that the spaces or voids existing between the individual fibers are reduced in size and narrowed to such an extent that the spaces or voids are converted to numerous aggregations of fine capillaries, the majority of which are located in the interior portion of the yarn and are hidden and enclosed inside the yarn. Therefore, when a woven fabric like this is processed with a molten bitumen, it is impossible to completely fill or saturate these fine capillary-form spaces with a molten bitumen which has a large molecular weight. For this reason, the bituminous sheet of the prior art which was made with a base consisting of the aforesaid woven fabric had a considerable number of residual fine voids which were not filled as was also the case with the bituminous felts made with paper base materials. As a result, the product having a woven fabric base had an imperfect water-insulating ability. Therefore, during use over an extended period of time, the sheet as a whole tended to develop a considerable amount of shrinkage.

These products made with woven fabric base materials comprise, when viewed from the aspect of their structure, portions of crossed yarns and portions which are voids defined by the staple fibers. In a coarsely woven fabric, these portions of voids or meshes do not contribute at all to the reinforcement of the layer of bitumen which is applied thereto. Besides, base materials made with woven fabrics are limited in mechanical strength depending on the direction of the applied tension. Such products exhibit a considerable mechanical strength in the directions in which the warp fibers and the weft fibers are disposed, but they are weak to a force which is applied in an oblique direction. While these products have an extensibility greater than that of the aforesaid products made with a paper base material, still their extensibility cannot be termed satisfactory;

Furthermore,. like the products made with paper, those products made with woven fabric bases will gradually and progressively decay when they are left in contact with water for an extendedperiod of time, and thus their mechanical strength is eventually lost.

A description will now be given of a product which is made by subjecting a base material, consisting of a mat molded with glass fibers, to a treatment with a molten bitumen. In this type of product, glass fibers are arranged in random directions within the mat, and the voids between the fibers are remarkably greater in size than those voids formed in the paper base material, so that the molten bitumen permeates thoroughly and completely into substantially all of the spaces and there is produced a condition in which there are hardly any spaces or voids which have not been filled with the molten bitumen.

Furthermore, glass fibers do not absorb moisture or water and they never decay. Accordingly, their resistance to water and resistance to decay are excellent. Also, products made with glass fiber base materials, as a whole, are of a tensile strength which is exhibited uniformly in all directions (nonoriented). These properties plus the great tensile strength of the glass fibers provide very efiective reinforcement of the layer of bitumen. However, a product made with a base material consisting of glass fibers lacks the needed resistance to tear.

Thus, a waterproof reinforcement sheet made with a glass fiber base material has various outstanding properties as compared with other sheet materials which are made with base materials consisting of paper or woven fabric. On the other hand, however, a sheet material which is made with a glass fiber base material has substantial drawbacks in other aspects. One such aspect is concerned with the basic nature of the product made with a glass fiber base material namely, that it is easily broken. This type of product is unexpectedly brittle to a bending force which is applied thereto so that the sheet material is easily broken. Another drawback results from the small degree of extensibility which is peculiar to glass fibers. This leads to the result that the sheet material made with glass fibers does not conform to the pulling force which is applied thereto, and in fact lacks resistance to even a slight degree of pulling force applied thereto. Thus, the sheet material breaksv easily.

For the foregoing reasons, a sheet material which employs glass fibers to constitute the base material to reinforce the layer of bitumen applied thereto, is satisfactory in its resistance to water and its resistance to decay. It bears a marked drawback such that, in case there occurs a displacement or movement of the face of the wall to which the water-insulating layer of the sheet material is applied and in case such displacement or movement causes a deformation of the water-insulating layer of the sheet material made with glass fibers to any slight extent, the sheet material will quite readily break and thus the most important purpose of insulating against water which was desired from the sheet material will not be accomplished.

As has been discussed above, these several types of waterproof reinforcement sheet materials of the prior art have their own drawbacks, respectively, and for this reason, they have not been completely satisfactory for use as the water or dampness-insulating waterproof reinforcement materials.

It is, therefore, the primary object of the present invention to provide a water or dampness-insulating waterproof reinforcement sheet material which completely eliminates all of these drawbacks of the aforesaid sheet materials of the prior art and which possesses all of the desired properties required of such sheet materials. The sheet material embodying the present invention is of such a structure as will be hereunder described and this structure is obtained according to the following procedure.

SUMMARY OF THE INVENTION The principle material comprising the sheet material of the present invention is substantially straight synthetic fibers having good heat resistivity and having a fineness measurement ranging from one-half to several scores of denier and a length of 50 mm. or more, preferably on the order of mm. or over. These fibers are first formed into a web in which the fibers are arranged in randomly overlying relationship. The web is then admixed with a small amount of binder solution to unite individual fibers together firmly and to fix the web and to convert the latter into a mat of a nonwoven fabric of a unique form. The resulting mat is impregnated with a molten bitumen of good quality, such as blown asphalt and compound asphalt, which exhibits a small susceptibility ratio. Granulesor powders of minerals of an appropriate type are sprinkled, as required, onto both the front and the reverse faces of the resulting mat to render these faces nonadhesive.

The properties of the water and dampness-insulating waterproof reinforcement sheet material of the present invention which is manufactured in such a way as has been described above has been compared with those of other conventional products and the results are as shown in the following table.

TABLE Conventional products using base material consisting of- Paper Cloth Glass Product of Organic Inorganic Natural Synthetic fiber the present fibers fi ers fibers fibers mat invention (1) Restriction to be imposed on the viscosity X X A A 0 0 of the saturating material or immersion fluid (bitumen) used. (2) Susceptibility of the filler to changes in X X A A 0 0 temperature, i.e. the thermo-susceptlbiiity of the product. (8) The amount of residual voids X X X X 0 0 (4) Flexibility A A O O X 0 (5) Mechanical strength (tensile strength and X X 0 0 A O tear stren th (6) Orientation concerning above A A X X 0 O (7) Elongation X X A A X 0 (8) Water absorbability and moisture ab- X A X 0 O O sorbability. (9; Resistivity to decay X 0 X 0 0 O (10 Deformation due to expansion and X 0 X A O O shrinking. (11) Price O A X X A A NOTE.O=desirable, A=tolerable, X=undesirabie, as insulating reinforcement material.

Except for the slight drawback as regards price, the properties of the product of the present invention are superior to any of other conventional products, and as a result, the product of the present invention is ideal for use as a waterand dampness-insulating and reinforcement sheet material.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following description will be directed to more specific points of the present invention. In the first place, some of the important reasons why the staple fibers which constitute the base material of the present invention are limited to polyvinyl alcohol synthetic fibers or polyester fibers having good heat resistivity may be explained as follows. (I) The employment of natural staple fibers is excluded in the present invention in view of their inherent tendency to decay easily during the course of use for a relatively short period of time. Avoiding such natural staple fibers, therefore, the present invention selectively employs fibers which have good resistance to decay. (2) The staple fibers constituting the base material are required to be flexible and to be of a sufficient extensibility. (3) The fibers are required to be such that they can be freely selected to have the appropriate fineness, length and the degree of crimp, as desired. (4) The staple fibers must have a sufficient resistance to heat which is necessary for the process of treatment with a molten bitumen.

Of the foregoing factors, items (1) through (3) constitute no substantial problems. With respect to the heat resistivity (item 4), it is necessary that the fibers are not affected in any way by the heat which is applied to them in case a bitumen which is heated so as to be in a molten state is applied to the base sheet-form web made with these staple fibers to saturate the latter web or in case the resulting sheet-form web is coated with such a molten bitumen. Ordinary synthetic fibers are mostly of a low resistance to heat, so that the selection of fibers, before use, are subjected, as a matter of fact, to no small restrictions.

The synthetic fibers which are suitable for use as the constitutional base material of the product of the present invention can be obtained by subjecting the fibers made from polyvinyl alcohol to a heat treatment and also to a chemical treatment, i.e. acetalization, to impart to the fibers a nature of being insoluble in water. In other words, Vinylon" (polyvinyl alcohol) fibers have a property that they can withstand a temperature of the order of 200 C. and are not affected by such temperature. This property plus various other desirable properties of Vinylon" fibers make these fibers most suitable for use as the material to constitute the base web for use in the product of the present invention.

a very high resistance to heat, but also they do not melt when they are subjected to heat. More specifically, these fibers are of a nature such that, when they are overheated by being exposed to a high temperature, they are not melted but develop cracking or gradually become carbonized. For this reason, Vinylon fibers are superior for use as the base material adapted to be treated with a molten bitumen.

The fibers which are made from a substance such as polyethylene terephthalate of the polyester group and which is known by the name Terylene, have a resistance to heat which is considerably higher than that of other synthetic fibers, and for this reason, these polyethylene terephthalate fibers are also suitable for use in the product of the present invention. Although these polyethylene terephthalate fibers are of a rather high apparent heat resistivity, or in other words, although the upper limit of the permissible temperature of the polyethylene terephthalate fibers is at a rather high level, these fibers have a nature that, when they are subjected to a temperature exceeding said upper limit, they melt easily. Therefore, when a base sheet material made with these polyethylene terephthalate fibers is subjected inadvertently to a high temperature above said upper limit in a treatment with a molten bitumen, they will shrink and, at the worst, they will Viny lon fibers not only have the advantage that they have be damaged to such an extent as completely would not retain any part of their original configurations. Accordingly, care must be taken in the treatment of the polyethylene terephthalate fibers.

Among the various synthetic fibers that are presently produced and supplied on a commercial as well as an industrial basis, there are found very few that are suitable for being used in the product of the present invention other than those described above.

According to the present invention, the fibers for use in the product of the present invention are restricted as regards the ranges of fineness and length of the fibers and the degree of crimp of the fibers. These restrictions are instituted because they all constitute important elements of the properties and the abilities of the fibers which can be used as the base web of the sheet material adapted for use in the insulation of water and dampness in construction requiring waterproof treatment and for use as a reinforcement material.

The following description will, therefore, be directed to the details of these restrictions imposed on the fibers.

With respect, first, to the fineness of the fibers, the permissible range is quite wide, it being in the range of from one-half to several scores of denier.

Synthetic fibers which are of a fineness smaller than onehalf denier are, as a matter of fact, not suited for general purposes in view of the difficulty which is encountered in their manufacture and in view also of the very limited demand. Even if it is intended to use fibers of such a small fineness, the base material made with these fine fibers will unavoidably lead to the formation of very narrow and small voids between the fibers and such small voids will be formed in great numbers, including in the interior portion of the web. Therefore, it is quite difficult to completely fill all of these numerous small voids with a molten bitumen without leaving a substantial number of unfilled voids.

On the other hand, staple fibers which are of a large fineness measurement, such as exceeding several scores of denier are not popular, excepting only those which are used for specific industrial purposes in some limited fields. It is to be noted that a base material made with staple fibers of such a large fineness measurement will contain areas of exceedingly coarse spaces between the staple fibers, giving rise to a great difficulty in the production of a firm combination between the adjacent individual staple fibers, with the result that the base material made with such staple fibers will have insufficient ability to reinforce the layers of bitumen applied.

The fineness of staple fibers which is suited for the object of the present invention preferably is in the range of from 2 to 10 denier for a sheet material of standard type, and in the range of from 10 to 20 denier for a sheet material used for special purposes. Staple fibers having fineness measurements in the aforesaid ranges are suitable for various purposes, and the overall properties of the staple fibers are most explicitly exhibited by those staple fibers lying within these two ranges.

Next, the length of fibers constitutes also an important element of the present invention. The restriction on the length of fibers which are the principal material of the product of the present invention to 50 mm. or more, preferably in the order of mm. or over, clearly distinguishes itself, with a marked contrast, from the length of the order of from 30 mm. to 40 mm. of the fibers constituting the principal material of ordinary nonwoven fabrics.

In the present invention not only the foregoing restrictions, but also the degree of crimp is limited in such a way that crimpless or only slightly crimped fibers are used. This is one of the important features of the present invention. Conventional ordinary nonwoven fabrics are formed by the employment, inevitably from the view point of the shape and form of the fibers which are the basic materials thereof and also for the reasons related to the manufacturing techniques, of fibers which are relatively small in length with the range being from 30 mm. to 40 mm., rarely in the range of from 60 mm. to 70 mm. and which are intensively crimped. Because these fibers are of appropriate properties to meet some specific purposes which are different from the objects of the present invention, they are used with satisfaction in each of these specific fields. However, these short, crimped fibers are not necessarily suitable for use as the material to reinforce the layer of bitumen and too thereby they fail to meet the important object'of insulating against water and dampness.

More specifically, a nonwoven fabric made with intensely crimped short fibers has increased degree of elongation but they have a small tensile modulus and also a small tensile strength. lf a large amount of binder solution is applied to these short, crimped fibers to improve their small tensile modulus and tensile strength, it will result in an increased uniting force between the individual fibers, and the fibers will be united together firmly, resulting in an enhanced mechanical strength of the nonwoven fabrics produced. However, the produced fabric has a shortcoming in that its elongation is reduced to a great degree. The physical property which is necessary for the waterand dampness-insulating reinforcement materials is that the sheet material has a high tensile modulus and a high elongability.

For comparison, the physical properties of various base materials will be shown in the following table.

Base material Tensile modulus Elongation Paper medium to large very small Fabric large small to medium Glass mat medium to large extremely small Conventional nonwoven fabric Present invention small to medium large large large The sheet material according to the present invention is a nonwoven fabric comprised of crimpless or slightly crimped, substantially straight fibers having a fineness ranging widely from one-half to several scores of denier and a fiber length ranging widely from 50 mm. to 1,000 mm The fibers are arcutting the fibers and without causing entanglement with the adjacently disposed fibers. The fabric is made by the following process. Fibers of a very small fineness of several tens of denier or less are treated by cutting tows of filaments by the use of an apparatus, such as a Perlok machine (random tensionbreaking system) or a Pacific converter (spiral cutting system), into a desired fiber length which, in the case of the filaments of such a small denier, preferably is between 50 mm. and 400 mm. Then, the cut tows of filaments are directly formed into slivers without causing any crimps at all or without causing any substantial crimps. With respect to those filaments having a large fineness of more than several tens of denier, they are first cut apart by any appropriate means into a desired fiber length of between 50 mm. and 1,000 mm., preferably between-250 mm. and 1,000 mm. for such fibers. Usually, these out fibers are then applied to a so-called drawing system which consists of a series of machines which are called a breaker," a spreader," and a finisher" which are the apparatuses used in the initial stage of producing ropes.

' The slivers thus obtained are such that the an; m

fibers constituting the slivers are all straight and, basically unlike other types 9 slivers such a se s l ve h fi es "a mar a i aranged in random direction with their initial crimpless shape I being retained, without any curtailment of their lengths by each other and they are disposed uniformly in a state in which they are substantially in parallel relation to the longitudinal length of the sliver. Moreover, the fibers are contained in the sliver in such a state that the head and the tail portions of the individual fibers are distributed at random and yet uniformly in the sliver. A multitude of parallel rows of such slivers are fed at a low speed and are firmly pinched in the nip ofa pair of nip rollers. Because the positions of the end portions of the individual fibers are located randomly, the fibers are released and freed one by one in succession after they have passed the nip point. Thereafter, the released free individual fibers are loosened by the needles on a rotating needled separator roller. The needles have a considerable length and have a round cross section and are spaced at appropriate intervals relative to each other so as to project straight and outward from the circumferential face of the separator roller on which the needles are secured. The roller is provided close to the nip rollers at a distance of several inches from the nip point and is rotated at a high speed. As a result, the fibers are scattered, in a flying motion and in an independent and separate state, onto the nearby face of a conveyor belt disposed near the discharge side of the separator roller. In this instance, by the use of a sliver as defined above, there is no entanglement of the adjacent fibers as a result of the operation of the separator roller, unlike ordinary card slivers or like slivers. The fibers are disposed in parallel relation to each other in the nip point so that when the fibers engage the needles which are rotated at a high speed, they are merely loosened and separated from each other and combed. Thus, they disperse quite satisfactorily without being cut or damaged by the needles.

This process of dispersing fibers provides a fabric of improved properties. The desirable dispersion of fibers becomes possible when slivers, such as Perlok sliver, converter sliver and/or drawing sliver which consist of straight fibers, are used. The aforesaid desirable dispersion of fibers is not achieved by using the conventional web-forming method in which ordinary crimped fibers are used and in which these crimped fibers are processed after they are made into card slivers by the use of carding machine or garneting machine.

By the adoption of the aforesaid method there has been obtained the advantage that fibers having an extremely large fineness such as several hundred denier and an extremely great fiber length such as several hundred millimeters, which could not have been processed using the conventional techniques, can be used.

Returning now to the stage of operation discussed previously, the step of operation in which the scattered individual separate fibers which have been released from the nip rollers and then the separator roller are accumulated one upon another in succession on a travelling net conveyor belt with the help of an air current in a well-known manner to form a uniform web containing randomly oriented fibers.

If desired the bituminous sheet of the present invention may be included in a laminated sheet also including webs of other materials such as paper, cloth, and other materials.

The description will next be directed to some of the examples of the present invention.

EXAMPLE l in length constitute the major part were accumulated continuously in random overlying relation on the surface of a moving belt of a conveyor in an appropriate manner to form a continuous web weighing averagely 150 g. per square meter; then the formed web was impregnated with a mixed solution of a binder consisting of an emulsion of a synthetic resin and a natural glue having a high molecular weight; thereafter the impregnated web was squeezed so that the weight of the fibers on a dry basis was five to 10 parts by weight relative to parts by weight of the total weight of the web and thereafter the squeezed web was subjected to drying in an air oven.

Then, the dried web was immersed in a bath of blown asphalt which was in the molten state by being heated at 200 C., said asphalt having a softening point of 90 C. and a penetration degree of 45, and the resulting web was squeezed in such a way that the adhering asphalt was of an amount, by weight, five to six times the weight of the fibers constituting the web. Thereafter, silica powder consisting of particles having a size passing through a sieve of the order of mesh no. 40 was sprinkled onto the faces of the resulting web. As a result, a bituminous sheet having a thickness of 1.4 mm. and an average weight of 1,600 g. per square meter was obtained.

The water-insulating reinforcement sheet material obtained in the aforesaid manner had the following mechanical properties (physical strength).

Tensile strength lengthwise 28.5 kg. crosswise 22.0 kg.

Extensibility lengthwise 42.5% crosswise 45.0%

mm. width 20 mm. span (between clamps) 50 mm, clamp speed per minute EXAMPLE 2 Crimpless cut fibers made from polyester resin fibers with a fineness of 3 denier and a length distribution ranging from 50 mm. to 200 mm. in such a way that those fibers of 150 mm. in length constitute the major part were accumulated continuously in random overlying relation on the surface of a moving belt of a conveyor in an appropriate manner to form a continuous web weighing averagely 150 g. per square meter; then the formed web was impregnated with a mixed solution of a binder consisting of an emulsion of a synthetic resin and a natural glue having a high molecular weight; thereafter the impregnated web was squeezed so that the weight of the fibers on a dry basis was five to 10 parts by weight relative to 100 parts by weight of the total weight of the web; and thereafter the squeezed web was subjected to drying in an air oven.

Then, the dried web was immersed in a bath of blown asphalt which was in the molten state by being heated at 180 C., said asphalt having a softening point of 70 C. and a penetration degree of 45, and the resulting web was squeezed in such a way that the adhering asphalt was of an amount, by weight, five to six times the weight of the fibers constituting the web. Thereafter, silica powder consisting of particles having a size passing through a sieve of the order of mesh no. was sprinkled onto the faces of the resulting web. As a result, a bituminous sheet having a thickness of 1.4 mm. and an average weight of 1,600 g. per square meter was obtained.

The water-insulating reinforcement sheet material obtained in the aforesaid manner had the following mechanical properties (physical strength).

Tensile strength 20 mm. span (Between clamps) mm. clamp speed per minute EXAMPLE 3 Cut fibers consisting of polyester fibers with a fineness of 6 denier and a length ranging from mm. to mm. were accumulated in random directions into a continuous web having an average weight of 50 g. per square meter, and then this web was subjected to locking which was performed by a machine called needle locker to cause entanglement of adjacently disposed staple fibers. Then the web was fixed with a small amount of a binder solution, and the resulting web was immersed in a coal tar pitch bath which was in a molten state due to being heated at 150 C. Thereafter, the resulting web as squeezed tightly and was cooled.

LII

The sheet material manufactured in the aforesaid manner was of such a form that there were present, throughout the faces thereof, numerous portions of holes of fine size where there was no fiber or tar pitch present, so that this sheet 5 material was suited for adhesively applying, by the use of a molten tar pitch, the face of this sheet material onto the face of the wall of a construction which is given waterproof treatment.

The sheet materials for insulating water and damp and for use in reinforcement which are manufactured according to the procedures described above are decisively superior to any other reinforcement sheet materials of any other type or to any other sheet materials produced according to any other manufacturing methods as far as the subject of reinforcing layers of bitumen with fibrous materials is concerned.

More specifically, in the base material of the product of the present invention, there are distributed, with substantial uniformity, only those voids which are of an appropriate average size such that same permit a molten bitumen having a high melt viscosity and having a superior quality to thoroughly permeate thereinto and fill up these voids, and there are hardly any voids present which are exceedingly small in size. For this reason, the base sheet material which has been impregnated thoroughly with a bitumen of good quality has excellent properties which are represented by low waterand dampness-absorbability and also by low thermosusceptibility which is such that the produced sheet material is able to retain its flexibility even when it is exposed to low temperatures. Furthermore, the structure of the sheet material wherein substantially straight staple fibers having a considerable length are disposed in random directions and that they are appropriately united to each other, imparts to the sheet material well-balanced physical properties wherein a high tensile modulus and a high degree of elongation, both of which are most desirous in a waterand dampnessinsulating reinforcement sheet material, are in a compatible relation with respect to each other. Besides, owing to the selective employment of synthetic fibers to form the base web, there is no fear that the web will become decayed during use for an extended period of time. In addition, the sheet material of the present invention is pliable and tough and is remarkably high in flexibility. As described above, the sheet material of the present invention is excellent because it possesses all of the desirable properties of the waterand dampness-insulating reinforcement sheet made with a base web consisting of the already described glass fiber mat which is regarded to be one of the most superior waterand dampness-insulating reinforcement sheet materials available at the present time, while it is completely free from all of the drawbacks of the reinforcement sheet material made with a glass fiber mat. In other words, the base web of the present invention may be termed as the best known form that has been developed in the aspect of the ability of the fibrous material to reinforce the layer of bitumen applied thereto.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

I. A bituminous sheet for use as a water and water vapor barrier, comprising:

a nonwoven web of substantially straight lengths of 50 mm.

to 1,000 mm. and fineness measurements between onehalf and 20 denier, the fibers in the web being arranged in a uniformly dispersed, random overlaying relationship so that the web has substantially a uniform density throughout;

a binder bonding said fibers with respect to one another;

and

a bituminous material impregnating said web and filling substantially all of the voids in the web and coating the fibers 95K?! hqebyj s nsaL niwen arz r vious sheet.

2. A bituminous sheet according to claim 1, including at least one layer of material laminated to said web.

3. A bituminous sheet for use a water and water vapor barrier comprising:

a nonwoven web of substantially straight, individual polyvinyl alcohol fibers, the individual fibers having lengths of 50 mm. to 1,000 mm. and fineness measurements between one-half and 20 denier, the fibers of the web being arranged in a uniformly dispersed random overlying relationship so that the web has a substantially uniform 

2. A bituminous sheet according to claim 1, including at least one layer of material laminated to said web.
 3. A bituminous sheet for use a water and water vapor barrier comprising: a nonwoven web of substantially straight, individual polyvinyl alcohol fibers, the individual fibers having lengths of 50 mm. to 1,000 mm. and fineness measurements between one-half and 20 denier, the fibers of the web being arranged in a uniformly dispersed random overlying relationship so that the web has a substantially uniform density throughout; a binder bonding said fibers with respect to one another; and a bituminous material interspersed between and around the fibers thereof, thereby forming a water and water vapor impervious sheet. 